1. Field of the Invention
The present invention pertains to a grasping device for arranging stacked workpieces so as to facilitate their removal from a stack. The device is adapted to be applied to a pickup and transporting machine whereby the machine delivers each piece within reach of an operator who relocates the piece for the purpose of performing additional manufacturing operations thereto as, for example, the assembly of pieces by means of a sewing machine.
2. Description of the Prior Art
As is well known to those conversant in the art, it is rather difficult to pick up a single piece of material manually from a pile or stack prior to the sewing operation which are formed to a particular size by means of cutting shears which cut the entire stack simultaneously that consists of twenty to fifty pieces. In an effort to increase the speed of removing the upper workpiece from a stack, a number of different devices have been made available which include pneumatic, mechanical and electro-mechanical devices. Pneumatic devices are based on the formation of a vacuum on the piece to be picked up, however, they are considered expensive and cannot be used in all types of factories as, for instance, in the smaller factories where compressed air systems are not available. Mechanical devices have also been available such as, for example, the one disclosed in U.S. Pat. No. 2,042,734. The teachings of this patent disclose two rollers which can move across the upper surface of the stack of pieces but are prevented from rotating so that they create a bunch or fold on the top piece which is raised from the piece immediately below and then can be moved away from the device by means of a movement parallel to the axis of the two rollers. The two rollers are adapted to rotate only during their backward movement, i.e. the reverse movement with respect to the one which has caused the separation of the top piece from the stack below. Although this device satisfactorily performs its intended function, it has not solved the problem as has the present invention of providing a device that will continuously grasp workpieces in a positive and simplified manner.